The present invention relates to a noise suppressing device suited for installation within a container, such as a fuel tank, to lessen and absorb the sloshing sound or the like of the liquid contained therein, i.e., to disperse or dampen the energy of the wave action.
Fuel tanks are provided with noise suppressing devices of various structures as shown in Japanese Utility Model Publication (KOKOKU) No. H06-6986, Japanese Patent No. 2719002, and Japanese Patent Publication (KOKAI) No. 2004-122902.
The structure disclosed in Japanese Utility Model Publication No. H06-6986 employs several sheets of mesh material that are stacked in layers at intervals by interposing raised ribs between the mesh material, and disposed and attached along the fuel tank's inner wall using brackets and the like. The operation is characterized such that when the fuel in the tank is sloshed around or moved by vibration or the like, the fuel within the tank passes through the mesh, and the wave action is dispersed, lessened or absorbed while the liquid passes through the intervals between the mesh materials.
The structure disclosed in Japanese Patent No. 2719002 has a spongy baffle part adhered to a section of the mounting bracket. In other words, the baffle part is a mass of entangled lint-like material of a predetermined size formed by extruding a molten resin as fine linear material through a number of nozzles onto a corresponding section of the bracket. The operation is characterized such that when the fuel in the tank is sloshed around or moved by vibration or the like, the liquid surge is dispersed, lessened or absorbed while the fuel passes through the baffle part having numerous small spaces and maze-like intervals.
The structure disclosed in Japanese Patent Publication No. 2004-122902 has a mesh material formed as a flat bag, numerous small pieces contained within the mesh bag, and a frame that holds the side edges of the bag. The operation is characterized by the synergy between the effect of lessening or absorbing the liquid surge of the fuel achieved by the two surfaces of the flat mesh bag and the effect of lessening or absorbing the liquid surge achieved through the spaces created by the small pieces in the bag as well as the numerous small pieces themselves.
The conventional devices described above have the following problems. The structure disclosed in Japanese Utility Model Publication No. H06-6986 is difficult to handle, as the mesh material is stacked in layers. The installation of the device in a fuel tank is time consuming, and the noise suppressing effect tends to vary depending on the installation conditions.
The structure disclosed in Japanese Patent No. 2719002 has low forming efficiency, as the spongy baffle part is created while a molten resin is extruded from nozzles. In addition, the noise suppressing effect tends to vary depending on the manner in which the resin is extruded through nozzles or the manner in which the resin hardens.
The structure disclosed in Japanese Patent Publication No. 2004-122902 can be more easily installed in a fuel tank than the device disclosed in Japanese Utility Model Publication No. H06-6986, and can more effectively stabilize the noise suppressing characteristics than the device disclosed in Japanese Patent No. 2719002. However, forming a mesh bag, storing small pieces in the bag, and disposing a frame makes it difficult to reduce manufacturing cost.
Accordingly, it is an object of the present invention to provide a noise suppressing device that solves all of the problems described above, and that has excellent installation and mass production qualities, and stable noise suppressing characteristics.
Further objects and advantages of the invention will be apparent from the following description of the invention.